1. Field of the Invention
The present invention generally relates to a magneto-generator (also referred to as the magneto-electric generator) for generating electric power under the action of electromagnetic induction taking place between magnets mounted on a flywheel and an armature winding during rotation of the flywheel and a method of manufacturing the magneto-generator. More particularly, the present invention is concerned with a method of manufacturing a flywheel provided with a plurality of magnets mounted on an inner peripheral surface of the flywheel.
2. Description of Related Art
For having better understanding of the concept underlying the present invention, description will first be made of a conventional flywheel type magneto-generator by reference to FIGS. 6, 7 and 8, in which FIG. 6 is a front view of a rotor of a conventional flywheel type magneto-generator disclosed, for example, in Japanese Patent Publication No. 81437/1994 (JP-A-6-81437), FIG. 7 is a sectional view of the same taken along the line VI—VI shown in FIG. 6 as viewed in the direction indicated by arrows, and FIG. 8 is a perspective view of a guard ring of the conventional flywheel type magneto-generator disclosed in the publication mentioned above. Referring to the figures, reference numeral 1 denotes a flywheel implemented in a substantially bowl-like shape (hereinafter also referred to as the bowl-shaped flywheel only for the convenience of description), reference numeral 2 denotes four magnets mounted on the peripheral wall of the flywheel 1 with equidistance between adjacent ones in the circumferential direction, numeral 3 denotes a guard annulus or ring of a substantially cylindrical shape which is adapted to be closely fit onto the inner surfaces of the magnets 2 which are disposed in a substantially annular array, numeral 4 denotes resin blocks filled at both sides and between the adjacent ones of the magnets 2 for fixedly securing the magnets 2 and the guard ring 3 to the flywheel 1 in a so-called integrated structure, and reference numeral 5 denotes a hub or boss formed in the flywheel 1 at a center portion of the bottom wall for coupling the rotor to a rotatable shaft (not shown).
In the rotor of the conventional magneto-generator implemented in the structure described above, four magnets 2 are disposed with equidistance therebetween on the inner peripheral surface of the flywheel 1 with the guard ring 3 being tightly fit onto the magnets 2 on the inner side thereof, wherein the voids or spaces defined between the inner peripheral surface of the flywheel 1 and the outer peripheral surface of the guard ring 3 are filled with the resin 4. In this manner, the magnets 2 and the guard ring 3 can fixedly be secured to the flywheel 1 through the medium of the resin 4.
FIG. 9 is a perspective view showing another example of the guard ring employed in the conventional magneto-generator. Further, FIG. 10 is a perspective view showing the state in which magnets are disposed on the guard ring shown in FIG. 9. As can easily be seen from FIG. 9, the guard ring 13 shown therein is destined for use in the magneto-generator in which a large number of magnets 2 are employed with the width thereof in the circumferential direction being reduced when compared with the structure shown in FIG. 8. Further, the guard ring 13 shown in FIG. 9 is formed with projections 13a for holding the magnets 2 equidistantly relative to one another.
In the conventional magneto-generator of the structure described above, the positions of the individual magnets 2 are sustained by means of the projections 13a formed in the guard ring 13 until the magnets 2 disposed on the flywheel 1 have been fixedly secured to the flywheel 1. In recent years, however, there has arisen a demand for sparing or omitting the guard ring 3 or 13 with a view to reducing the number of parts constituting the magneto-generator. In this conjunction, it is further noted that the presence of the guard ring 3 or 13 increases the distance between a generator coil of the stator (not shown) and the magnets 2, which is unfavorable for realization of enhanced performance of the magneto-generator. For this reason, the guard ring 3 or 13 should preferably be omitted.